Grinding stand for rock drills



p 2, 1958 B. E. R. LOFQVIST ETAL 2,849,839

GRINDING STAND F OR ROCK DRILLS 2 Sheets-Sheet 1 Filed Feb. '7, 1957 INVENTORS BQ/ljt Erik Ragnwald l 'fquisi CarL Barge Eben "78.17

BPMJWA PM) ATTORNEYS P 1958 BE. R. LOFQVIST ET AL GRINDING STAND FOR ROCK DRILLS 2 Sheets-Sheet 2 Filed Feb. 7, 1957 INVENTORS 5e Eberman 8 Pub ATTORNEYS United States Patent GRINDING STAND FOR ROCK DRILLS Bengt Erik Ragnwald Liifqvist, Gavle, and Carl lliirje Eberman, Sandviken, Sweden, assignors to Sandvikens .lernwerks Aktiebolag, Sandviken, Sweden, a corporation of Sweden Application February 7,1957, Serial No.'638,797 7 Claims. (Cl. 51--55) The present invention relates 'to grinding stands and in particularto stands adapted'for' the grinding ofrock drill bits of the percussion type.

The stand in accordance with'the invention is easily movable and effective for most accurate grinding ofthe drill 'bit.

An object of the invention is to provide a grinding stand comprising a support body and two legsextending downwardly therefrom in a divergent manner, the body including a clamping or claw-device for holding the bit end of the drill which is to be ground and the shank'portion of the drill when so held also extending downwardly at an angle away from the two legs to thus form the third leg of a tripod type of support. A :grinding machine in the form of a'motor driven grinding wheel is mounted-on the support'body in suchmannerthat the face of the grinding wheelcan'be movedin-a rocking manner back and forth across "the face 'ofthedrill bit in a path at thepropergrinding angle, andthe invention also'provi'des means-whereby thejoperator is able to increase the pressure of the grinding -wheel against the face-of the drill bit, the'constructional arrangement being such that the operator is able to pass the'grinding wheel back and forth across the face of 'thebit with one hand and change the grinding pressure, between successive grinding passes, with the other hand.

A further object is to provide a drill grinding stand having three legs arranged in the manner of a tripods-o as to support the same when not in use,'and wherein one of the legsof the tripod is automaticallyraised ofi the floor upon insertion of a rock drill bit 'for grinding, the drill bit litslf thenbecoming the thirdleg of the tripod support, and the stand including "a simple claw device for gripping the end of the drill bit in such manner that the'grippi'ng action is established'in a simple manner bythe reaction forces attributable to thetripod type of support for the massesinvolved and which exert'an upward force on thedrill bit in its claw thus holding the bit firmly in the *g-rindingpositionwithout the need. for

"any positive clamping device. The foregoing as-well asother-objects and advantages of the invention will become more apparent from .the

following detailed description of atypical embodiment thereof and the'accompanying drawings wherein;

Fig. l is a view in perspective showing the grinding stand with'a drill bit inserted therein and being ground;

:Fig. 2 is a view in side elevation of the grinding stand;

Fig. 3"is a top 'planvi'ew of the stand with certain parts broken awayto show detailed structure;

Fig. 4 is a-view of the stand'inendlevationyand Figs. 5 and 6' are fragmentary 'vi'ewsdown'to an enl-arged' scale to show-certain details of construction.

With reference now to the drawings, the grinding stand is seen to be, comprised of a body member i'n-the form of a metallic elongated platejl'l of. suitable thickness to provide the necessary strength and toithe. lower face of which, is secured. at-one end of .1he..plate,.such as. .by

welding, a pair of pipe sockets 12, 13 which extend ranged at an angle to each other in order to: form a 2,849,839 Patented Sept. 2, 1958 "ice downwardly therefrom in a divergent manner and in a .plane'substantially perpendicular to the plate 11. The .sockets 12, 13 are adapted to receive legs 14, 15 respectively, which may be formed from drill rods cut mto 'suitablelengths, or the legs may be made from any other suitable rod material having the necessary strength.

A third socket 16 extends downwardly from plate 11 in a plane forming an angle with the plane containlng 'thesockets 12, 13 and is adapted to receive a third leg 17 which is shorter than legs 14, 15. The legs '14, 15 and 17 are secured within their respective sockets by any suitable means such as by set screws 18, and such legs by virtue of their mutually divergent relationship establish a tripod type of support for the drill stand when not in use.

Secured to the upper side of plate 11 is a simpleclaw type of clamping device by which a drill 'bit'is vheld firmly in grinding position without the need forany'sp'ecial screw actuated or other positive clamping means. The clamping device 20 comprises an essentially inverted L-shaped member 21 secured as by welding to plate 11, and of suitable length to receive anappreciable portion ;of the bit'end 22a of a drill rod 22. The member 21 will be. evident. that leg 17 will be raised from the lfloor and that the drill rod 22 now constitutes the third leg of the tripod support. Moreover, due to thisarrangement, the support forces reacting from the weight, which the'tripod carries, upon the drill rod 22 .is' such as to. produce an upward force on the latter which causes it 'to bear most firmly against the upper and lower claws 23,24 and thereby prevents the drill bit end 2'2a-.rom becoming loosened in the clamping device'as it is ground. In addition to the claws 23, 24, the member '21-is provided at its front end with an inclined stop flange 25 disposed at such an angle as to engage the face 226 of .the drill. bit opposite-from face. 22c which isbeing1gronnd so as to hold the bit at the proper angular position. for grinding relative to the grinding wheel.

Depending from the lower face of plate 11 at-the opposite end thereof and normal thereto andin the plane of the socket 16 is a pivot assembly comprising a cylindrical member 26 mounted for rotation about itslon- .gitudinal' axis xxv seen in Fig. 2. A plate member 27 is securedat one end as by welding,-to. the cylindrical member 26, and has secured to its opposite end by a hinge assembly 28 a second plate member 29-Whichis located generally parallel with and in spaced relation from the. plate member 27, the hinge axis y-ybeing located. parallel with the grinding face of the grinding wheel and the function of the hinge assembly being: such as to permit the position of the grinding member'to'fbe- .rnovedcloser, by increments, to'the face-of the bit be- .ing. ground- The plates 27 and 29lie in' plane'siparall'el with. axis y-y.

As seen in Fig. 2, the axes x-x and y -y are arcorrect angle for grinding the surfaces 22b, 22c. of the drill. bit inrelation to the longitudinal axis of the latter, the grinding angle being, for example, 55".

The plate member 29 has secured to it a grinding machine 31 having a motor driven grinding wh'eel'32 and which is covered in part by an arcuate protection shield 33. The motor 34 in the illustrated embodiment Other types of motors form such as, for example, the hollow cylindrical form shown in the drawing or it can have a disc formation, etc. As will later be more clearly understood, the invention makes it possible to move the grinding wheel back and forth across the face of the drill bit by imparting a similar movement to the grinding machine 31 and for this purpose it will be seen that the latter is provided with a handle as adapted to be grasped by the right hand of the operator, as indicated in Fig, 1.

As explained above, the improved grinding stand includes an arrangement for manually increasing, by adjustable increments, the pressure exerted by the end face of the grinding wheel 32 against the surface of the drill bit being ground. To this end it will be seen from Fig.

" 3 that a threaded bolt 37 has a T-shaped head 37a which passes through an elongated slot 33 in the plate member 29 and is then turned 90 and brought to rest in a locking recess 39 provided at the outer face of plate 29 and which extends normal to the long axis of slot 38 and thus prevents the bolt 37 from turning about its axis.

Surrounding the bolt 37 is a helical spring 44 One end of spring 40 adjacent the plate 29 is received in and bears against a cup 41 surrounding bolt 37 and bearing against the inner face of plate 29, and the opposite end of spring 40 bears against the inner face of plate 27. The opposite end of bolt 37 passes through an aperture in plate 27 and threads through a hand wheel 42 which bears against the outer face of plate 27. The spring 40 is held in compression between its cup 41 and the inner face of plate 27 and thus urges the hingedly connected plates 27 and 29 apart. As the hand wheel 42 is turned i. e. threaded downwardly upon the shank of bolt 37, the plates 27 and 29 will thus be drawn closer together, thus relocating the end face 32:: of the grinding wheel closer against the face 220 of the drill bit.

If desired, the support member 11 may be provided with a suitable type of indexing means, not shown, for indicating the position of the drill bit.

The operation of the grinding device is deemed to be obvious from the foregoing description but can be summarized as follows:

Before using, the drill stand rests upon its three legs 14, 15 and 17. A rock drill 22 with a bit end 22a which needs regrinding is then inserted longitudinally into the claw type clamping device 26 between the claws 23, 24 until the upper face 22b at the cutting edge of the bit comes to rest against the stop flange 25. The drill 22 being longer than leg 17, the latter thus no longer will reach the floor, and the drill 22 takes over the function of the third leg of the tripod support. The grinding wheel 32 is now adjusted by means of the hand wheel 42 until the grinding end face 32a bears against the bit face 22c to be ground. The grinding machine 31 is now started and the operator, with his hand on and using handle 36, rocks the grinding machine 31 and its supporting components comprising plates 27, 29 and cylindrical pivot member 26 about the aXis x-x thus causing the rotating face 32a of'the grinding wheel to execute a corresponding back and forth movement across the bit face 220. After a few passes of the grinding face 32a across In conclusion it is to be understood that the improved grinding stand in accordance with the invention is not only usable for grinding single cutter rock drills as shown but also other types of rock drills and other types of drills or similar tools which include a working edge at the end of a shaft. Moreover, it will be understood that various minor changes in the construction and arrangement of parts can be made without, however, departing from the spirit and scope of the invention as defined in the appended claims.

We claim:

1. In a grinding stand for drill rods such as rock drills and the like, the combination comprising a support body, a pair of supporting legs extending downwardly from said body, means carried by said body for holding the bit end of the drill rod in such position relative to said pair of supporting legs that said drill rod cooperates therewith as the third leg of a tripod type of support, first and second elongated plate-like supporting members arranged in generally side-by-side spaced relation and being interconnected at one end thereof by a first pivot means, second pivot means at the opposite end of said first supporting member pivotally interconnecting the same with said support body, and a grinding machine carried by said second supporting member, said first and second supporting members being rotatable as a unitary assembly about the axis of said second pivot means thereby to move the grinding component of said grinding machine across the face of the drill bit to be ground.

2. A grinding machine as defined in claim 1 wherein the respective axes of said first and second pivot means form an angle with each other.

3. A grinding machine as defined in claim 1 and which further includes means for moving said second supporting member about said first pivot means closer to said first supporting member and thereby correspondingly moving the grinding component of said grinding machine closer to the face of said drill bit.

4. A grinding machine as defined in claim 3 wherein said means for moving said second supporting member closer to said first supporting member comprises a threaded bolt having the head end thereof attached to one of said supporting members and passing through an aperture in the other supporting member, and a hand wheel threaded onto the end of said bolt and bearing against the face of said other supporting member.

5. A grinding machine as defined in claim 4 and which further includes a helical spring surrounding said bolt, the opposite ends of said spring bearing against the confronting faces of said first and second supporting members.

6. A grinding machine as defined in claim 1 and which further includes a handle member on said grinding machine for facilitating movement thereof and of said first and second supporting members as a unitary assembly about the axis of said second pivot means.

7. In a grinding stand for drill rods such as rock drills and the like, the combination comprising a support body, a pair of supporting legs extending downwardly from said body, claw means carried by said body for holding the bit end of the drill rod in such position relative to said pair of supporting legs that said drill rod cooperates therewith as a third leg of a tripod type of support, the bit end of said drill rod being kept in place in said claw means solely by the weight acting downwardly on said legs, a third leg extending downwardly from said body and whichcooperates with said pair of legs to also establish a tripod type of support in the absence of the drill rod, first and second elongated plate-like supporting members arranged in generally side-by-side spaced relation and being interconnected at one end thereof by a first pivot means, second pivot means at the opposite end of said first supporting member pivotally interconnecting the same with said support body, the respective axes of said first and second pivot means forming an angle with each other, and a grinding machine carried by said second supporting member, said first and second supporting members being rotatable as a unitary assembly about the axis of said second pivot means thereby to move the grinding component of said grinding machine across the face of the drill bit to be ground, and means engaging said first and second supporting members for drawing said second supporting member and hence also 6 the grinding component of the grinding machine carried by the latter towards said first supporting member thereby to effect a corresponding movement of said grinding component closer to the face of said drill bit.

References Cited in the file of this patent FOREIGN PATENTS 132,853 Sweden Sept. 4, 1951 

